Alert archive / Idaho / Special Weather Statements in 2021
Special Weather Statement, NWS Missoula, MT
NWS Missoula, MT issued this special weather statement at Jul 21, 2021, 1:43 PM MDT for Lemhi County, Idaho. It was in force for 17 min. No storm report in the archive falls inside the area while it was in force.
The area
The outline as issued.
The facts
- Issued
- Jul 21, 2021, 1:43 PM MDT (19:43 UTC)
- Expired
- Jul 21, 2021, 2:00 PM MDT
- In force
- 17 min
- Issued by
- NWS Missoula, MT
County Lemhi County, ID
The radar
The Missoula radar (KMSX), 187 km from the middle of the area, began a volume at 19:44 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
The nearest sounding before it
Boise Airport, ID (KBOI), launched 12:00Z, 7.7 hours before the alert went out and 273 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 62 J/kg
- Mixed-layer CIN
- -356 J/kg
- Mixed-layer LCL
- 2257 m above ground
- 0-6 km bulk shear
- 24 kt
- 0-1 km storm-relative helicity
- 32 m²/s²
- 0-3 km storm-relative helicity
- 127 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
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</html>What forecasters said that day
The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Missoula, MT wrote its last area forecast discussion before this special weather statement went out at Jul 21, 3:38 AM MDT, 10 hours 5 minutes earlier.
Area forecast discussion, Jul 21, 3:38 AM MDT, 10 hours 5 minutes before
Area Forecast Discussion
National Weather Service Missoula MT
338 AM MDT Wed Jul 21 2021
.DISCUSSION...A shortwave of energy can be seen on satellite this
morning, and is currently moving through southeast Washington into
the Idaho panhandle. Showers and isolated thunderstorms have been
associated with this wave overnight. It will move into northwest
Montana towards sunrise, bringing the threat of a few lightning
strikes, especially near the Idaho/Montana border.
Another round of showers and thunderstorms is anticipated this
afternoon and evening. They will likely form once again across
Lemhi County and southwest Montana early this afternoon, shifting
into west-central Montana by late afternoon and northward along
the Continental Divide into this evening. With increasing jet
energy aloft, there is potential that some of these storms could
become strong. The main threat will be for gusty and erratic
winds, which could reach up 50+ mph with the stronger storms.
While brief heavy rain is still possible with storms, flash
flooding concerns are lower today as storms should be moving
faster due to increased winds aloft. A weak cold front will stall
over northwest Montana and the Idaho panhandle this afternoon,
bringing some increased winds. Critical fire weather conditions
are possible along this boundary, particularly through north
central Idaho close to the Washington and Oregon borders. A red
flag warning remains in effect.
The weak cold front will move through the rest of western Montana
and central Idaho on Thursday. Much drier air will move in behind
this front and will combine with breezy west to northwest winds to
create a period of critical fire weather conditions. Fire weather
watches remain in effect for the afternoon and evening hours.
Thunderstorms will again be possible, but with the main area
shifted further south through far southwest Montana and Lemhi
County.
Friday will be a dry, breezy and warm day across the region. Warm
and dry conditions will then follow into the weekend as high
pressure re-establishes.
&&
.AVIATION...A wave of energy will continue to initiate nocturnal
convection early this morning, primarily across northwest
Montana. Breezy winds to 20kts and a few lightning strikes can be
anticipated with these storms. Scattered thunderstorms will fire
once again this afternoon with the focus across west- central and
southwest Montana, southward into Lemhi County. A few of these
storms could become strong, with the main threat being gusty
outflow winds up to 45 kts. Convection will likely initiate
as early as 21/1800z, becoming more numerous by 21/2100z. KMSO,
KGPI, KBTM and KSMN all could see thunderstorms in the vicinity
through 22/0300z. A weak cold front will stall through the Idaho
panhandle and northwest Montana this afternoon, bringing the
potential for some breezy westerly winds up to 20kts for these
areas.
Visibility reductions will continue as local and regional
wildfires produce varying amounts of smoke. Periodic convection
will help to mix the atmosphere, allowing for improved air
quality at times.
&&
.MSO WATCHES/WARNINGS/ADVISORIES...
MT...Fire Weather Watch from Thursday afternoon through Thursday
evening Bitterroot...Deerlodge/West Beaverhead...East
Lolo...Flathead/Glacier Park...Kootenai...Salish and
Kootenai Reservation...West Lolo.
ID...Fire Weather Watch from Thursday morning through Thursday
evening Clearwater/Nez Perce.
Red Flag Warning from 11 AM this morning to 9 PM PDT this
evening Palouse/Hells Canyon.
&&In the hours before
Special weather statement, Jul 21, 1:43 PM MDT, 0 minutes before
Special Weather Statement
National Weather Service Missoula MT
143 PM MDT Wed Jul 21 2021
IDZ009-010-212000-
Eastern Lemhi County ID-Western Lemhi County ID-
143 PM MDT Wed Jul 21 2021
...SIGNIFICANT WEATHER ADVISORY FOR NORTH CENTRAL LEMHI COUNTY UNTIL
200 PM MDT...
At 143 PM MDT, Doppler radar was tracking a strong thunderstorm 7
miles northwest of Salmon, moving northeast at 25 mph.
Pea size hail and winds in excess of 40 mph will be possible with
this storm.
Locations impacted include...
Salmon, Leesburg and Carmen.
LAT...LON 4525 11421 4552 11378 4550 11376 4548 11376
4545 11378 4543 11376 4541 11377 4539 11373
4533 11374 4528 11368 4525 11369 4512 11405
TIME...MOT...LOC 1943Z 233DEG 23KT 4523 11405The office that day
Everything else NWS Missoula, MT issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 21, 12:17 PM MDT | Fire Weather Watch | MSO | Beaverhead, Deer Lodge, Granite, Jefferson, Madison, Powell and 1 more | 25 hr |
| Jul 21, 12:17 PM MDT | Red Flag Warning | MSO | Flathead, Glacier, Lake, Missoula, Powell, Sanders | 33 hr |
| Jul 21, 2:44 PM MDT | Special Weather Statement | MSO | Ravalli | 31 min |
| Jul 21, 2:57 PM MDT | Special Weather Statement | MSO | 33 min | |
| Jul 21, 3:49 PM MDT | Special Weather Statement | MSO | Ravalli | 26 min |
| Jul 21, 3:51 PM MDT | Special Weather Statement | MSO | Powell | 24 min |
| Jul 21, 4:15 PM MDT | Special Weather Statement | MSO | Silver Bow | 15 min |
| Jul 21, 4:40 PM MDT | Special Weather Statement | MSO | Granite | 35 min |
| Jul 21, 4:53 PM MDT | Special Weather Statement | MSO | Missoula | 37 min |
| Jul 21, 5:06 PM MDT | Special Weather Statement | MSO | Missoula | 24 min |
| Jul 21, 5:12 PM MDT | Severe Thunderstorm Warning | MSO | Missoula | 19 min |
| Jul 21, 5:33 PM MDT | Special Weather Statement | MSO | Missoula | 27 min |
| Jul 21, 5:36 PM MDT | Severe Thunderstorm Warning | MSO | Missoula, Powell | 24 min |
| Jul 21, 5:43 PM MDT | Special Weather Statement | MSO | Deer Lodge | 17 min |
| Jul 21, 5:44 PM MDT | Special Weather Statement | MSO | Missoula | 16 min |
| Jul 21, 2:16 PM MDT | Areal Flood Advisory | MSO | Lemhi | 119 min |
| Jul 21, 4:18 PM MDT | Special Weather Statement | MSO | Lemhi | 27 min |
Nearby
Special Weather Statements in Idaho, 2021Every special weather statement in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.